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The entire electric utility industry is in the midst of unprecedented uncertainty and change. The continuously changing energy market forces-such as customer preferences, new technologies, public policy, regulation, and the cost of renewables-are the cause of this dynamic and uncertain future. Thus, no one can predict the next five to ten years, much less the next 30 years. Critical to the business strategy are flexibility and the ability to pivot and adjust as markets and circumstances change, while continuing to fulfill the utility's obligation to serve.

Many companies will continue to fulfill their obligation to serve by providing a reliable and resilient grid for all customers. As the amount of renewable energy generation continues to grow, companies will make investments in an intelligent grid that will enable them to integrate more renewables and distributed resources, to obtain access to more data to operate the system more efficiently, to better understand customers' needs, and to provide more customer options (e.g., demand response programs).

To more fully understand the effect of increased renewable energy generation at the expense of firm fossil fuel fired generation, we need to understand the characteristics of the electrical grid. Grid system security, or operating reliability, is defined by the North American Electric Reliability Corporation (NERC) as the ability of the system to withstand sudden disturbances. These disturbances or contingencies can be the loss of generation or electrical faults that can cause sudden changes to frequency, voltage, and/or current. The design of the transmission system is based on the inherent characteristics of synchronous generators (i.e., firm fossil fuel fired generation) to effectively deliver power from central station generators to distribution load centers while optimizing efficiency and maintaining a high level of reliability.

A synchronous generator is essentially a large rotating electro-magnet that converts mechanical energy to electrical energy that is transferred to the electrical system through a rotating magnetic field. An electrical system with more synchronous generators has a high inertia and a strong magnetic coupling, making it less susceptible to disruptions from disturbances like a generator trip or an electrical fault. The proliferation of solar- and wind-generated renewable energy has resulted in a displacement of synchronous generation, reducing the inertia of the overall system and lessening grid stability. Therefore, until grid technology more fully evolves, there will be a continuing reliance on firm fossil fuel fired generation to ensure the stability of the system.

Companies will need to seriously consider an optimal mix of fossil fuel fired generation (i.e., synchronous generation) as existing generation ages and as new flexible and efficient generation technology becomes available. This will allow for the integration of large amounts of variable renewable energy resources on the grid. Some fossil fuel fired generators may be nearing the end of their existing power purchase agreements (PPAs), which may now be under negotiation for renewal. Many of the previously desired characteristics (e.g., high capacity factors and availability) may now be interpreted as restrictive in not allowing a facility to operate with the flexibility that will be required in the future. Operating restrictions include limitations on startup times, ramp rates, and minimum load. 

Specifically, future operating scenarios may require stationary combustion turbines to operate at low loads during periods when renewable energy sources are available or during periods when a facility's energy requirements are reduced during a full or partial maintenance outage. These low load level requirements may be in ranges where there have been sensitivities to compliance concerns (e.g., less than 50% load). 

Trinity is aware of these evolving issues and is currently supporting clients as they negotiate PPAs and other market forces. Trinity has relevant knowledge of the necessary operational flexibility required by today's fossil fuel fired assets, notably during transient and low load operation, and has successfully obtained the associated permit flexibility. For more information, please contact Trinity at (800) 229-6655 or complete the Contact Us form on our website.